Glucosamine inhibits LPS-induced COX-2 and iNOS expression in mouse macrophage cells (RAW 264.7) by inhibition of p38-MAP kinase and transcription factor NF-kappaB

Glucosamine supplements are very promising nonsteroidal anti-inflammatory agents widely used for the treatment of arthritis in animals and humans. In this study, we have proposed the molecular mechanism underlying the anti-inflammatory properties of glucosamine hydrochloride (GLN) using mouse macrophage cell line (RAW 264.7). Treatment with GLN inhibited LPS-stimulated nitric oxide (NO) production. Western blotting and RT-PCR analysis showed that GLN treatment decreased LPS-induced inducible nitric-oxide synthase (iNOS) and cyclooxygenase-2 (COX-2) protein and mRNA expression in RAW 264.7 cells, respectively. To further elucidate the mechanism of inhibitory effect of GLN, we studied the LPS-induced phosphorylation of mitogen-activated protein kinases (pp44/42 and pp38). Our results clearly indicated that GLN treatment resulted in a reduction of pp38, whereas activation of p44/42 was not affected. In addition, LPS-induced activation of nuclear factor-kappaB (NF-kappaB) DNA binding suggests an inhibitory effect of GLN. These results indicate that GLN suppresses the LPS-induced production of NO, expression of iNOS and COX-2 by inhibiting NF-kappaB activation and phosphorylation of p38 MAP kinase.     

Sialoglycoprotein isolated from Carassius auratus eggs promotes osteoblast differentiation via targeting the p38 mitogen‐activated protein kinase‐dependent Wnt/β‐catenin and BMP2/Smads pathways

In the current study, sialoglycoprotein isolated from eggs of Carassius auratus promoted MC3T3‐E1 cells proliferation and differentiation, as assessed by MTT, mineralized nodule formation in vitro, as well as new osteoid formation in neonatal mouse calvarias ex vivo. Further research revealed that Ca‐SGP facilitated osteogenesis via activating BMP2/Smads, Wnt/β‐catenin, and p38MAPK signaling pathways. What is more, p38MAPK inhibitor SB203580 down‐regulated related mRNA and protein expression of BMP2/Smads and Wnt/β‐catenin signaling pathways, suggesting that p38MAPK pathway might be important for activation of BMP2/Smads and Wnt/β‐catenin pathways in Ca‐SGP‐induced osteoblastic differentiation. In conclusion, it was demonstrated that Ca‐SGP promotes osteoblasts differentiation via activating p38MAPK‐dependent BMP2/Smads and Wnt/β‐catenin signaling pathways, which may provide basis for the use of Ca‐SGP as a potential agent to treat bone loss‐associated diseases such as osteoporosis.

Practical application

Carassius auratus eggs are one of the major by‐products during fish processing and contain sialoglycoprotein which plays an important role in biological functions. However, they have not been high‐value utilized. This study demonstrated that Sialoglycoprotein isolated from eggs of C. auratus (Ca‐SGP) promoted MC3T3‐E1 cells proliferation, differentiation and mineralized nodule formation in vitro, as well as neonatal mouse calvarias formation ex vivo, which may provide basis for a novel application of C. auratus eggs as a functional food used to accelerate bone formation.     

Suppression of IL‐8 Release by Sweet Olive Ethanolic Extract and Compounds in WiDr Colon Adenocarcinoma Cells

Oxidative stress can stimulate the secretion of pro‐inflammatory cytokines. Interleukin‐8 (IL‐8) has been implicated in the pathogenesis of inflammatory bowel disease and the metastatic spread of colorectal cancer. The flowers of Osmanthus fragrans (sweet olive) are used to alleviate dysentery with blood in the bowel, as well as stomach ache and diarrhea. However, the evidence of their therapeutic effects on these symptoms remains unclear. In the present study, the protective effects of sweet olive flower ethanolic extract (OFE) against oxidative stress in WiDr cells was assessed by evaluating its 1,1‐diphenyl‐2‐picrylhydrazyl (DPPH) free radical scavenging activity. In addition, cellular IL‐8 secretion was evaluated. Notably, high‐performance liquid chromatography showed verbascoside to be the primary constituent in OFE; it exhibited a DPPH scavenging activity with an IC₅₀ of 8.23 μg/mL. Moreover, OFE (1 to 100 μg/mL) showed a potent, dose‐dependent inhibitory effect on H₂O₂‐induced IL‐8 secretion in WiDr cells. Nine compounds were isolated from OFE based on a protective effect‐guided purification process. Of these compounds, 5 phenolic compounds—verbascoside, phillygenin, tyrosol, methyl 4‐hydroxycinnamate, and eutigoside A—reduced IL‐8 secretion at 10 μg/mL treatment concentrations. Further analysis showed that the anti‐inflammatory effects of OFE likely occurred via nuclear factor‐κB pathway inhibition, which attenuates IL‐8 secretion in cells. Collectively, these data suggest that OFE could be developed as an agent that suppresses IL‐8 secretion to treat chronic inflammatory diseases.     

Dietary calcium decreases plasma cholesterol by down‐regulation of intestinal Niemann–Pick C1 like 1 and microsomal triacylglycerol transport protein and up‐regulation of CYP7A1 and ABCG 5/8 in hamsters

Scope: It has been shown that calcium supplementation favorably modifies plasma lipoprotein profile in postmenopausal women. The present study investigated the interaction of dietary calcium with genes of transporters, receptors and enzymes involved in cholesterol metabolism. Methods and results: Forty‐eight ovariectomized hamsters were fed one of the four diets containing 0, 2, 6 and 8 g calcium per kg. Plasma total cholesterol (TC), triacylglycerols (TG), and non‐high density lipoprotein cholesterol were dose‐dependently decreased, whereas high‐density lipoprotein cholesterol (HDL‐C) was dose‐dependently increased with the increasing dietary calcium levels. Dietary calcium had no effect on protein mass of hepatic sterol regulatory element binding protein‐2 (SREBP), liver X receptor‐alpha (LXR), 3‐hydroxy‐3‐methylglutaryl‐CoA reductase (HMGR), LDL receptor (LDLR) and cholesterol‐7α‐hydroxylase (CYP7A1). However, dietary calcium up‐regulated the mRNA levels of hepatic CYP7A1 and intestinal ATP binding cassette transporters (ABCG5/8) whereas it down‐regulated the intestinal Niemann‐Pick C1 like 1 (NPC1L1) and microsomal triacylglycerol transport protein (MTP). In addition, dietary calcium increased the activity of intestinal acyl coenzyme A: cholesterol acyltransferase 2, while it decreased plasma cholesteryl ester transport protein (CETP). Conclusion: Beneficial modification of lipoprotein profile by dietary calcium was mediated by sequestering bile acid absorption and enhancing excretion of fecal cholesterol, via up‐regulation of mRNA CYP7A1 and intestinal ABCG 5/8 with down‐regulation of mRNA NPC1L1 and MTP.